You will love the Rías Baixas!
You should go to Las Islas Cíes (you can take a boat from Vigo). It is spectacular! Also, going to Finisterre is wonderful! The town of Cambados (famous for their horreos) is a must-see too! I love the city of Pontevedra too, as a place to walk around and visit the old section. I assume you will go to Santiago! It is an amazing city to visit! (remember the fiestas are July 25 there!) and as you go north to Las Rías Altas I can recommend the towns of Malpica and Camariñas (especially if you like to see the artisans at work making the lace (encaje de bolillos) there. The Roman lighthouse in A Coruña is worth a visit too. Then there is the town of Betanzos near there that I especially love~ As you can see, there are so many nice towns in GALICIA!! This is where my family is from, so if you have any other questions, ask away and I will try to help! Enjoy planning!!